What is the use of Aminopterin in hybridoma production?
1. to kill unfused myeloma cells
2. to kill non-antibody secreting hybrids
3. to kill unfused splenic cells
4. to kill non-specific antibody secreting hybrids

 

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Detailed Explanation:

The correct answer is: 1. to kill unfused myeloma cells

What is Hybridoma Technology?

Hybridoma technology is a method used to produce monoclonal antibodies (mAbs). It involves the fusion of:

• B-lymphocytes (from an immunized mouse spleen) that produce a desired antibody but have limited lifespan.

• Myeloma cells (cancerous plasma cells) that can divide indefinitely but don’t produce antibodies.

The resulting hybrid cells (hybridomas) combine the best of both: they secrete specific antibodies and are immortal.

Role of Aminopterin:

Hybridoma cells are selected using HAT medium (Hypoxanthine, Aminopterin, and Thymidine). In this medium:

• Aminopterin blocks the de novo DNA synthesis pathway by inhibiting dihydrofolate reductase (DHFR).

• This forces all cells to rely on the salvage pathway for nucleotide synthesis, which requires the enzymes HGPRT and TK.

Why is Aminopterin Important?

• Unfused myeloma cells (which are HGPRT-deficient due to genetic modification) cannot use the salvage pathway, so they die in the presence of aminopterin.

• Unfused spleen cells die naturally because they are not immortal.

• Only hybridomas, which inherit HGPRT from spleen cells and immortality from myeloma cells, survive in the HAT medium.

Thus, aminopterin is crucial for selecting only the fused hybrid cells capable of producing the desired monoclonal antibodies.